wouldn't that produce the same effect as using Farmer's Reducer? If I understand it correctly, Farmer's has bleach and fixer so that the bleached image cannot be redeveloped?

Dan

That's correct. Farmer's Reducer is nothing but potassium ferricyanide (bleach) plus fixer. Using them together or sequentially has the same effect.
However, the mixture has the benefit that one can immediately see the bleaching progress. Unfortunately, it is not very stable due to a chemical reaction between ferri and fixer, causing it to lose its entire strength within 10-15 minutes.